In this post I take a look at the various BMW suspensions (OE and M-Performance) to get a bit of insight on the original design by looking at ride frequencies.
Common Perceptions
BMW suspensions are colloquially referred to as "base," "M-Sport," "xDrive," and "M-Performance." Among these there are common perceptions that sDrive vehicles can have base, M-Sport, and M-Performance suspensions available, and xDrive vehicles only really have the base suspension, even if the EDC/Adaptive-M dampers are selected. We'll find out this isn't necessarily true.
Methods
To find the ride frequencies I looked up the official vehicle weights and weight distributions to get the F/R corner weights. Then I used RealOEM (and other sources to verify if it didn't seem right) to find the weight of unsprung parts and subtracted that from the corner weights to get the "sprung corner weights." Lastly, for the springs I used the BMW ETK system to look up the various spring PNs per model/config and some proprietary information to calculate the frequencies.
Ride Frequency Findings
One thing that surprised me after doing all the calculations across the US F30/31/32/34/36 models was that it really looks like BMW has target frequencies for the front suspension across their various suspension levels. For example, on base suspensions the target appears to be ~1.2Hz, for M-Sport/M-Adaptive it's ~1.33Hz, and for M-Performance it's ~1.55Hz.
For the rear ride frequencies BMW tends to make them 8-12% higher than the front to achieve flat ride/fast settling. That said, there are some exceptions to this. For some reason on all F32s, the front/rear frequency ratio is less (2-8%), and the F32 M-Perf suspensions can even get into a pitch regime where the front and rear ride frequencies are about equal. My guess is that this is to make the F32 feel sportier, without actually giving it more capability.
For comparison, when I did the same activity on F8x vehicles, the F80/82 base suspension front was about ~1.35Hz, competition pack ~1.45Hz, and the rear ride frequencies were 15-20% higher. The M2 suspensions have even higher front frequencies around the 1.5-1.55Hz range, which is probably why people say those cars feel more responsive than F80/82's.
M-Perf suspensions bring the front and rear ride frequencies close to that of the M2s, so vehicles with those should feel similarly responsive.
Model/Chassis Trends
Before, I spoke of the perception of "base" and "M-Sport" suspensions, but the reality is that some models' "base" is more like others' "M-Sport." For example, the F30 sDrive cars have the different base and M-Sport suspensions we're all used to, however F32 and F36 base and M-sport package cars have the same springs. This explains why people say the F32/36 base handles better than F30 base, because they already come with M-Sport springs.
Additionally, for xDrive vehicles the Adaptive-M suspensions come with stiffer springs than the base suspensions, which makes their ride frequencies equal to sDrive M-Sport. This differentiates the xDrive base, and Adaptive-M suspensions more than previously commonly thought!
Another thing I've seen are that 4cyl xDrive front springs are the same as 6cyl sDrive front springs in many cases. This means that 4cyl xDrive cars can get most of the way to an M-Performance suspension by ordering the same front/rear springs as the 6cyl sDrive version, the M-Performance rear shocks (which fit both sDrive and xDrive), and means the only missing piece are the M-Performance front struts. An aftermarket front strut where the mfg overdamps it (for the OE springs) to make it feel sporty can probably get you close to the M-Perf front strut, or you can have a custom shock tuner do one for you. This commonality between 4cyl xDrive and 6cyl sDrive fronts should also be helpful information for people looking at aftermarket springs and what those mfgs recommend vs how OE is set up.
Additionally, on heavier rear-end cars (like F31/F34, or F30 330e) aftermarket rear springs might not be any stiffer than OE, and actually softer! That could cause you to poorly tune your ride frequencies and end up in a pitch regime if the front spring rate is increase and the rear is decreased. This is one of the reasons I think that companies who recommend the same coilover for F31/33/34 as F30 are doing you a disservice. They simply haven't done the calculations and seen how their product really works on those platforms.
Please don't PM me about springs for your car, 1) so we can keep the info public to help others and 2) I'm not your personal consultant, unless you're buying one of the spring sets I have for sale 
or want to pay me a consulting fee, haha.